The schemata for Lil' Smoky and the Pet Bombling are now Bind on Pickup drops from Gnomeregan. I know, I know, Gnomeregan is terrible, but most pet collectors are so overleveled for that place that this new method of getting the recipes should be dramatically easier. The Pet Bombling appears to be a 100% drop off of Thermaplugg, the final boss of the dungeon. Lil' Smoky is slightly less reliable, but not by much. He drops off of the Arcane Nullifiers and only the Arcane Nullifiers, as far as testers have found. That makes sense, considering Lil' Smoky shares their model.

If you're going to be hunting down these bad (and smelly) boys come patch 3.1, Gnomeregan is the place to be. Kaliope even has some further advice on tracking down Lil' Smoky, should you need it. Good luck on your hunt!